1. Technical Field
The present invention relates to an active metal brazing material used for bonding materials such as ceramics.
2. Background Art
As the active metal brazing materials used for mutual bonding of ceramics and bonding of a ceramic and a metal, there has hitherto been known a Ag—Cu—Ti alloy, which Ti as an active metal component has been added to a Ag—Cu alloy. The active metal brazing material is frequently used as follows: the raw materials are melted in a vacuum melting furnace, the resulting melt is cast, the resulting cast is processed, for example, by rolling processing into a thin plate shape, and the thin plate is stamped out by press working into an intended shape to be used.
Examples of the problems associated with the active metal brazing material include the workability of the active metal brazing material; specifically, in the foregoing production/processing step, the material tends to undergo cracking, wire breaking and rupture. This is because in the Ag—Cu—Ti alloy, at the time of the cast solidification, an intermetallic compound composed of Cu and Ti, having a size as large as 50 to 100 μm precipitates in the Ag—Cu alloy matrix. The intermetallic compound is extremely hard and strong, hence is not divided in the subsequent plastic working, and thus maintains nearly the size thereof at the precipitation stage. Accordingly, a processing performed to a shape close to the compound particle size causes, for example, cracking. Specifically, for example, a processing into a plate shape is restricted by the thickness limit of 100 μm, and a processing to a thickness equal to or less than the limit is made impossible. Herein, with the recent progress of the miniaturization of electronic/electric components, the active metal brazing materials used are also required to be of a thin type or of a fine type; in this context, conventional Ag—Cu—Ti alloy active metal brazing materials are far from meeting such market demands.
In this connection, it is not meant that there are no method for reducing the particle size of the intermetallic compound composed of Cu and Ti, which precipitate in the Ag—Cu alloy matrix of the Ag—Cu—Ti alloy. For example, in Patent Literature 1, it is known that the Ag—Cu—Ti alloy is maintained when melted at a temperature equal to or higher than the melting point of the compound composed of Cu and Ti, and quenched when cast.